Can lid

ABSTRACT

A can lid includes a score line provided on an outer peripheral edge side of a disk-shaped panel portion; a rivet portion provided in the panel portion and adjacent to an inner side of the score line in a radial direction; a tab including an attachment portion including a rivet hole to be attached to the rivet portion, a tip portion continuous with the attachment portion, and a finger hook portion formed on a side opposite to the tip portion across the attachment portion; and an auxiliary score line formed in the panel portion and including a first part and a second part, the first part extending in an arc shape on an inner side of the rivet portion in a radial direction of the panel portion, the second part being continuous with the first part.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a Continuation Application of PCT Application No. PCT/JP2021/020028, filed May 26, 2021 and based upon and claiming the benefit of priority from Japanese Patent Application No. 2020-092838, filed May 28, 2020, the entire contents of all of which are incorporated herein by reference.

FIELD

The present invention relates generally to a can lid used for a can.

BACKGROUND

Conventionally, as can lids used for cans for food products, so-called full-open type can lids, which are opened on the entire surface, are widely used. In a can for a food product, after filling the can with contents, the final product is formed by retort treatment, and an internal pressure of the can becomes negative. However, as disclosed in Japanese Patent Application KOKAI Publication No. 2012-131518 and Japanese PCT National Publication No. H2-502814, it has been proposed in recent years to use a full-open type can lid even in a can having a positive internal pressure.

Such a can lid is provided with a ring-shaped score line which is formed on a peripheral edge side of a panel portion and defines an opening piece, and an auxiliary score line formed around a rivet portion for attaching an opening tab. In an initial stage of an opening operation of the tab, when the tab is lifted by hooking a finger on a finger hook portion of the tab, the auxiliary score line is broken by a second kind of leverage with a tip portion of the tab as a fulcrum, the finger hook portion of the tab as a point of force, and the rivet portion as a point of action.

Due to the breakage of the auxiliary score line, the panel portion around the rivet portion is easily deformed, and the finger hook portion of the tab is easily lifted. When the tab is further lifted from the state in which the auxiliary score line is broken, the ring-shaped score line in the vicinity of the tip portion of the tab is broken by the first kind of leverage with the rivet as a fulcrum, the finger hook portion of the tab as a point of force, and the tip portion of the tab as a point of action. Thereafter, as the finger hook portion of the tab is pulled upward, the ring-shaped score line is broken in a circumferential direction, and the opening piece is removed from the can lid.

SUMMARY

In the case of a can in which the internal pressure is positive, since a central portion of a can lid expands into a dome shape due to the internal pressure of the container, a tip portion of a tab is located on an inclined surface that is inclined downward toward an outer peripheral side, and therefore the tip portion of the tab may be displaced toward the outer peripheral side of the can lid during an opening operation and the opening operation may not be appropriately performed.

According to one aspect of the embodiments, a can lid includes a disk-shaped panel portion; a score line provided on an outer peripheral edge side of the panel portion; a rivet portion provided in the panel portion and adjacent to an inner side of the score line in a radial direction; a tab including an attachment portion including a rivet hole to be attached to the rivet portion, a tip portion continuous with the attachment portion, and a finger hook portion formed on a side opposite to the tip portion across the attachment portion; and an auxiliary score line formed in the panel portion and including a first part and a second part, the first part extending in an arc shape along the rivet portion on an inner side of the rivet portion in a radial direction of the panel portion, the second part being continuous with the first part, wherein if a straight line passing through a center of the rivet portion and a tip of the tab is a first straight line and a straight line passing through the center of the rivet portion and orthogonal to the first straight line is a second straight line, the second part extends in a direction along the second straight line and is located on a center side of the panel portion with respect to the second straight line.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view showing a configuration of a can lid according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing the configuration of the can lid.

FIG. 3 is a cross-sectional view showing a configuration of an essential part of the can lid.

FIG. 4 is a cross-sectional view showing a configuration of a panel portion used for the can lid.

FIG. 5 is a cross-sectional view showing a configuration of an essential part of a can for which the can lid is used, and an example in which the can lid expands by an internal pressure.

FIG. 6 is a cross-sectional view showing an example of a state when a tab is opened in the example in which the can lid expands by the internal pressure.

DETAILED DESCRIPTION

Hereinafter, a configuration of a can lid 1 including a tab 12 according to an embodiment of the present invention will be described with reference to FIGS. 1 to 6 .

FIG. 1 is a plan view showing a configuration of the can lid 1 according to the embodiment of the present invention, and FIG. 2 is a cross-sectional view showing the configuration of the can lid 1. FIG. 3 is a cross-sectional view showing a configuration around a rivet portion 32 of the can lid 1, and FIG. 4 is a cross-sectional view showing a configuration of an auxiliary score line 33 provided in a panel portion 21. FIGS. 5 and 6 are cross-sectional views showing a configuration of a can 100 for which the can lid 1 is used and showing a state in which the panel portion 21 of the can lid 1 expands into a dome shape. FIG. 5 shows a configuration before an opening operation by the tab 12, and FIG. 6 shows a configuration at the time of the opening operation by the tab 12.

As shown in FIGS. 1, 2, 5, and 6 , the can lid 1 is, for example, a so-called full-open type which is opened on the entire surface. As shown in FIGS. 5 and 6 , the can lid 1 is a member of the can 100 in which, for example, a retort food, a beverage such as a carbonated beverage or an alcoholic beverage, or the like is held as a content, and constitutes an opening portion for dispensing the content from inside the can 100 to the outside. The can lid 1 is integrated with a can body 101 of the can 100 by seaming. As a result, in the can 100, the can lid 1 and the can body 101 are airtightly fixed by a seamed portion 100 a.

The can 100 is, for example, a positive pressure can, the inside of which is under a positive pressure. The can 100 may be either a two-piece can or a three-piece can. The contents are not limited to beverages or food products, and may be something other than beverages and food products. That is, the contents considered applicable include a variety of things that can be sealed in the can 100.

As shown in FIGS. 1 and 2 , the can lid 1 includes a can lid body 11 and a tab (can lid tab) 12. The can lid 1 is formed by pressing a metal plate to form the can lid body 11 and the tab 12 in another process, and then fixing the tab 12 to the panel portion 21. Examples of the metal plate forming the can lid body 11 include an aluminum alloy plate and a surface-treated steel plate having a resin film formed on the surface thereof. Examples of the metal plate forming the tab 12 include an aluminum alloy plate.

As shown in FIGS. 1 to 3, 5, and 6 , the can lid body 11 includes the panel portion 21, a ring-shaped groove portion 22 provided on an outer peripheral edge of the panel portion 21, and a flange portion 23 provided on an outer peripheral edge of the ring-shaped groove portion 22.

As shown in FIGS. 1 to 4 , the panel portion 21 is formed in a disk shape. The panel portion 21 includes a score line 31, a rivet portion 32, an auxiliary score line 33, a protection portion 34, and a finger insertion concave portion 35. The panel portion 21 may also have a display portion 36 or the like such as braille for displaying the content of the can 100. Further, the panel portion 21 may have a convex portion or a concave portion for product identification, design, reinforcement, or the like.

As shown in FIG. 6 , the score line 31 is broken by an opening operation of the tab 12. By being broken, the score line 31 creates an opening portion of the can lid 1 in the panel portion 21. In other words, the score line 31 surrounds a region which becomes an opening piece when the opening portion of the can lid 1 is formed. Since the can lid 1 in the present embodiment is a full-open type, the score line 31 is formed in a circular shape or an approximately circular shape as shown in FIG. 1 , for example. When the score line 31 is broken, as shown in FIG. 6 , a portion of the panel portion 21 that is on an inner side of the score line 31 in a radial direction can be removed as an opening piece together with the rivet portion 32 from a portion of the panel portion 21 that is on an outer side of the score line 31 in the radial direction.

The score line 31 is a groove that constitutes a fragile portion that enables a part of the panel portion 21 to be broken in the shape of the opening portion by an external force. As shown in FIG. 3 , the score line 31 is, for example, a wedge-shaped groove provided on an outer surface of the panel portion 21, and a part of the panel portion 21 is formed to be thin by the score line 31. Here, the outer surface of the panel portion 21 is a main surface exposed to the outside in a state where the can body 101 of the can 100 is provided with the can lid 1, that is, a surface constituting an upper surface of the can 100.

The score line 31 is arranged, for example, in the protection portion 34. The score line 31 is not limited to a circular shape, and may have, for example, a configuration in which the score line 31 is formed in a partially intermittent arc shape, most of the panel portion 21 is opened, and an opening piece that is opened is partially continuous with the panel portion 21.

As shown in FIGS. 1 to 3, 5, and 6 , the rivet portion 32 is provided on one main surface of the panel portion 21, specifically, on the outer surface of the panel portion 21. The rivet portion 32 is provided on an outer peripheral edge side of the panel portion 21 and on the center side with respect to the score line 31. That is, the rivet portion 32 is provided adjacent to the inner side of the score line 31 in the radial direction.

The rivet portion 32 is formed in a columnar shape in such a manner as to project from one main surface of the panel portion 21. The rivet portion 32 is formed by drawing a part of the panel portion 21 into a cylindrical shape. By swaging the rivet portion 32 after the tab 12 is arranged, the tab 12 is fixed to the panel portion 21. In FIGS. 1 to 3, 5, and 6 , the rivet portion 32 is shown in a state after swaging.

As shown in FIGS. 1 to 4 , the auxiliary score line 33 is formed in the vicinity of the rivet portion 32 of the panel portion 21. A part of the auxiliary score line 33 is broken at the time of the opening operation of the tab 12. The auxiliary score line 33 includes, for example, a main score line 41 and a sub score line 42 which is provided in parallel to the main score line 41 and on a side opposite to the rivet portion 32 of the main score line 41.

The main score line 41 is a groove that constitutes a fragile portion that enables a part of the panel portion 21 to be broken in the shape of the opening portion by an external force. The main score line 41 is, for example, a wedge-shaped groove provided on the outer surface of the panel portion 21. A part of the panel portion 21 is formed thin by the main score line 41. As shown in FIG. 6 , the main score line 41 is broken at the time of the opening operation of the tab 12 to allow the rivet portion 32 to move upward.

As shown in FIG. 4 , the main score line 41 includes a first part 41 a, a pair of second parts 41 b continuous with the first part 41 a, and a pair of third parts 41 c respectively continuous with the pair of second parts 41 b. In the main score line 41, the first part 41 a, the pair of second parts 41 b, and the pair of third parts 41 c are continuous.

As shown in FIG. 4 , the first part 41 a extends in an arc shape along the rivet portion 32 on an inner side of the rivet portion 32 in the radial direction of the panel portion 21. When a straight line passing through the center of the rivet portion 32 and the tip of the tab 12 is defined as a first straight line X, and a straight line passing through the center of the rivet portion 32 and orthogonal to the first straight line X is defined as a second straight line Y, the first part 41 a is arranged on an inner side of the second straight line Y in the radial direction of the can lid 1. That is, a curvature radius of the first part 41 a is set to be larger than a radius of the rivet portion 32 before being swaged.

As shown in FIG. 4 , each of the second parts 41 b is continuous with the first part 41 a and extends in a direction along the second straight line Y. The second part 41 b is, for example, formed in a straight line. A continuous portion of the first part 41 a and the second part 41 b is formed in, for example, an arc shape having a predetermined curvature radius. The second part 41 b is arranged on the inner side of the second straight line Y in the radial direction of the can lid 1. Preferably, a distance between the second part 41 b and the second straight line Y in the direction of the first straight line X is in a range of 0.2 to 2.0 mm. As shown in FIG. 4 , the third parts 41 c are respectively continuous with the second parts 41 b and curve in a direction away from the second straight line Y. For example, the third parts 41 c are formed in a plurality of arc shapes having different curvature radii and having curvature centers on the inner side of the second straight line Y in the radial direction of the can lid 1. The third parts 41 c are arranged on the inner side of the second straight line Y in the radial direction of the can lid 1.

The sub score line 42 is provided on an inner side of the main score line 41 in the radial direction of the panel portion 21. The sub score line 42 is formed in parallel to the main score line 41. The sub score line 42 is, for example, a wedge-shaped groove provided on the outer surface of the panel portion 21. The sub score line 42 is formed to have a depth smaller than that of the main score line 41. That is, a thickness of a portion of the panel portion 21 where the sub score line 42 is provided is formed thicker than a thickness of a portion of the panel portion 21 where the main score line 41 is provided. A part of the panel portion 21 is formed thin by the sub score line 42.

As shown in FIGS. 2 to 6 , the protection portion 34 is formed by the panel portion 21 being folded in a ring shape. The protection portion 34 is, for example, formed by being folded four times on an inner side of the outer peripheral edge of the panel portion 21 in the radial direction and on an outer side of the rivet portion 32 in the radial direction. That is, the protection portion 34 is formed by arranging the panel portion 21 in five layers. The score line 31 is formed in the protection portion 34 and in the third layer of the panel portion 21.

When the tab 12 is opened and the score line 31 is broken, the protection portion 34 constitutes an outer protection portion 34 a that protects an inner peripheral edge of a portion of the panel portion 21 broken along the score line 31 that is present in the can body 101, and an inner protection portion 34 b that protects an outer peripheral edge of a portion (opening piece) of the panel portion 21 broken along the score line 31 that is removed from the can body 101. The outer protection portion 34 a is constituted by a three-layered panel portion 21, and a folded portion is present at an inner peripheral edge of the opened panel portion 21. The inner protection portion 34 b is constituted by a three-layered panel portion 21, and a folded portion is present at an outer peripheral edge of a portion separated from the opening of the panel portion 21.

In other words, as shown in FIG. 3 , the protection portion 34 has an upper layer 34 c formed by the folded panel portion 21 in the first and second layers and located on an outer surface side of the can lid 1, a lower layer 34 d formed by the folded panel portion 21 in the fourth and fifth layers and located on an inner surface side of the can lid 1, and an intermediate layer 34 e formed by the folded panel portion 21 in the third layer and located between the upper layer 34 c and the lower layer 34 d. The outer protection portion 34 a is formed by the upper layer 34 c and a part of the intermediate layer 34 e, and the upper layer 34 c is located above the score line 31 and functions as a protection portion after the score line 31 is broken. The inner protection portion 34 b is formed by a part of the intermediate layer 34 e and the lower layer 34 d, and the lower layer 34 d is located below the score line 31 and functions as a protection portion after the score line 31 is broken.

The finger insertion concave portion 35 is located below a rear end of the tab 12 on which a finger is hooked, and is recessed from the outer surface of the panel portion 21.

The groove portion 22 is a ring-shaped recess which is provided continuously with the outer peripheral edge of the panel portion 21 and projects to a can body side when the panel portion 21 is fixed to the can body. The groove portion 22 has a function to improve the pressure resistance of the can lid 1.

The flange portion 23 is seamed with an opening end of the can body 101. The flange portion 23 is provided with a sealing resin layer on a surface contacting the can body 101.

As shown in FIGS. 1 to 3 , the tab 12 includes an attachment portion 51, a tip portion 52, and a finger hook portion 53. In the tab 12, the attachment portion 51, the tip portion 52, and the finger hook portion 53 are formed integrally. When the tab 12 is opened by a finger or the like hooked on the finger hook portion 53, the tip portion 52 presses a portion of the panel portion 21 that is adjacent to the inner side of the score line 31 in the radial direction to break the score line 31.

As shown in FIG. 3 , the attachment portion 51 is formed in a plate shape, and has a rivet hole 51 a. The attachment portion 51 is continuous with the tip portion 52 and the finger hook portion 53. The rivet hole 51 a is formed to have an inner diameter into which the rivet portion 32 can be inserted. The rivet portion 32 inserted into the rivet hole 51 a is swaged so that the attachment portion 51 is fixed to the panel portion 21 by the rivet portion 32.

The tip portion 52 is formed on a tip side of the tab 12. The tip portion 52 has a tip formed in an arc shape or a polygonal shape. The tip portion 52 is formed by, for example, bending double an outer peripheral edge excluding the tip.

The finger hook portion 53 is a portion on which a finger is hooked in order to lift the tab 12 at the time of the opening operation of the tab 12. As shown in FIGS. 1 and 2 , for example, the finger hook portion 53 includes a ring hole 53 a and is formed in a ring shape. As a specific example, the finger hook portion 53 is formed in a rectangular frame shape having arc-shaped corner portions. The finger hook portion 53 is formed on a side opposite to the tip portion 52 across the attachment portion 51. When the tab 12 is attached to the panel portion 21, a rear end of the finger hook portion 53 faces the finger insertion concave portion 35. The finger hook portion 53 is formed by, for example, bending an outer peripheral edge and an inner peripheral edge of the ring hole 53 a so that they are doubled.

In the can lid 1 formed as described above, as shown in FIG. 4 , the auxiliary score line 33 is located on an inner side of the second straight line Y passing through the center of the rivet portion 32 in the radial direction of the can lid 1. Thus, even in a positive pressure state in which the can lid 1 expands into a dome shape with the center portion of the can lid 1 as an apex, the leverage at the time of lifting the tab 12 can be reliably exerted. That is, it is possible to prevent the tip portion 52 of the tab 12 from being displaced to the outer peripheral side of the can lid 1 at the time of the opening operation of the tab 12. Thus, when the tab 12 is opened, the tip of the tip portion 52 can press a portion of the panel portion 21 that is adjacent to the inner side of the score line 31 in the radial direction, so that an appropriate opening operation can be performed by the tab 12. Thus, the can lid 1 can improve lid openability even for a positive pressure can by the shape of the auxiliary score line 33 and a positional relationship between the rivet portion 32 and the auxiliary score line 33.

As described above, the can lid 1 according to one embodiment of the present invention has sufficiently easy lid openability even when used for a positive pressure can.

Note that the present invention is not limited to the embodiment described above. For example, in the above-described example, the auxiliary score line 33 has the configuration in which the second part 41 b of the main score line 41 is formed in a straight line as an example in which the second part 41 b is extended in the direction along the second straight line Y, but the configuration is not limited thereto. The second part 41 b may have a curved shape instead of a straight line shape as long as it can be approximated to extend in the direction along the second straight line Y. If the second part 41 b has a curved shape, the curvature radius of the second part 41 b is set to an arc shape larger than the curvature radii of the first part 41 a and the third part 41 c.

In the above example, the can lid 1 is used for a positive pressure can, but is not limited thereto and may also be used for a negative pressure can.

The present invention is not limited to the above-described embodiments, and can be modified in practice without departing from the spirit of the invention. The embodiments may also be implemented by combining them appropriately, in which case the combined advantages are obtained. Furthermore, the embodiments include various inventions, and such various inventions can be derived by properly combining the structural elements disclosed in connection with the embodiments. For example, even if some structural elements are deleted from all the structural elements shown in the embodiments, when the problem can be solved and the advantageous effects can be obtained, such a configuration in which those structural elements are deleted can be extracted as an invention. 

What is claimed is:
 1. A can lid comprising: a disk-shaped panel portion; a score line provided on an outer peripheral edge side of the panel portion; a rivet portion provided in the panel portion and adjacent to an inner side of the score line in a radial direction; a tab including an attachment portion including a rivet hole to be attached to the rivet portion, a tip portion continuous with the attachment portion, and a finger hook portion formed on a side opposite to the tip portion across the attachment portion; and an auxiliary score line formed in the panel portion and including a first part and a second part, the first part extending in an arc shape along the rivet portion on an inner side of the rivet portion in a radial direction of the panel portion, the second part being continuous with the first part, wherein if a straight line passing through a center of the rivet portion and a tip of the tab is a first straight line and a straight line passing through the center of the rivet portion and orthogonal to the first straight line is a second straight line, the second part extends in a direction along the second straight line and is located on a center side of the panel portion with respect to the second straight line.
 2. The can lid according to claim 1, wherein a distance between the second part and the second straight line in an extending direction of the first straight line is set within a range of 0.2 to 2 mm. 